1. Field of the Invention:
The invention relates to a reactor column for the implementation of anaerobic decomposition processes with a fixed bed, through which the reaction fluid travels upward.
2. Description of the Prior Art:
The execution of anaerobic decomposition processes on carrier-fixed microorganisms is increasing in importance. The anaerobic purification of waste water appears particularly beneficial. In this process, in contrast to the activated sludge process, relatively small amounts of residual sludge are formed and the energy balance of the entire process is more favorable, since on the one hand, there is no need to introduce oxygen, and on the other hand, the biogas formed can be used as an energy source.
A prerequisite for a commercial application of the process is high efficiency per unit of volume and per unit of time, that is, for a given reactor volume, the maximum quantity of waste water substrate must be treated in the shortest possible time.
Recently, therefore, processes have been developed for the immobilization of active biomasses which make it possible to deal with quantities of waste water like those treated commercially in an acceptable length of time using reactors of an acceptable size. But a problem which occurs with the use of beds of small-particle carrier materials, for example, with a size of 5 to 15 mm, which exhibit a surface large enough for cell fixation, is that excessive sludge is formed after a period of extended operation, which leads to clogging and limitations of diffusion, and to the formation of graft flows. In addition, the amount of biogas contained in the reaction mixture increases as the reaction proceeds, which has an adverse effect on the treatment system (solid/liquid/gas).
For these reasons, reactor columns with small-particle carriers, with fixed beds more than approximately 2 meters in height, are no longer considered optimal.
A reduction of the specific activity of the column, in order to prevent the increasing clogging of the fixed bed, or a corresponding limitation of the height of the reactor, does not appear very economical, since on the one hand, the overall reactors would have to be larger, and on the other hand, the ground space required for a "flat" design with the appropriate column cross section, or a number of parallel columns, would not be economical.